Gravitational pouring of molten metal, aluminum in particular, into molds during sand casting can promote oxidation, introduce impurities, and create turbulence causing gas bubbles and oxide inclusions that are detrimental to the aluminum casting.
To avoid the problems associated with traditional gravitational pouring, capital-intensive metal pouring systems, such as high pressure die castings, and bottom filling processes using pressure are used. Bottom filling processes rely on rotation of the mold after fill or on very large top risers that provide feed metal after shrinkage. Both of these approaches can introduce defects.
Therefore, there is still a need to develop mold fill processes that reduce capital investment in new equipment, lower maintenance costs and reduce defects associated with gravitational pouring.